This invention relates in general to respirator masks and in particular to a new and useful lung-controlled valve for a respirator mask which have a positive interior mask pressure.
A similar lung-controlled valve is known from the German Journal "Dragerheft" No. 306, pages 16-22, (1976).
The known lung-controlled valve establishes the positive pressure in the respirator mask by the fact that its control diaphragm is tensioned by spring force in such a way that on reaching a certain pressure inside the mask (static pressure), the inlet valve is closed. As soon as this given pressure is fallen short of, the inlet valve opens and supplies respiratory air until the given pressure is reached again. In the known lung-controlled valves, the spring exerts it's maximum force on the diaphragm in the position in which the valve just starts to open for establishing the static pressure. When drawing relatively large quantities of air and in particular when breathing briskly, the forces diminish due to the spring characteristic, so that at maximum diaphragm stroke and completely opened valve the smallest opening force acts on the diaphragm and hence also the least pressure prevails in the interior of the mask.